Conventional devices and techniques used to treat bone fractures include external fixation structures, such as Illizarov and Taylor Spatial Frame, and internal fixation structures, such as plates, nails, pegs, screws, and other fixators. Each type of technique relies on providing proper stability to the bone so that it can heal naturally by normal growth and regeneration processes.
Fractures that involve load bearing bones, such as femurs and tibias, are particularly difficult to treat due to their substantial load bearing requirements. Devices used must provide sufficient axial, torsional and bending strength across the fracture site to support the loading. External fixation devices and methods typically encompass the fracture site and sit external to the patient's skin. They can be cumbersome, uncomfortable, carry a risk of infection, and limit ambulation and therefore often fail to fully satisfy a patient's desires for care and treatment.
Internal devices are installed on or in the fractured bone across the fracture site. An example is an intramedullary (IM) nail that is installed longitudinally into the intramedullary canal of a fractured bone. Some structures used in internal repair provide less than optimal biocompatibility and support for the patient's normal biological healing processes. Furthermore, after the fracture is healed, a second surgery may be required to remove the IM nail from the patient. This increases the risk of infection to the patient and cost to the healthcare system. Hence, considerable research and development has focused on techniques for replacing traditional fracture fixation devices with biodegradable (also referred to as resorbable, bioerodible, degradable, or bioabsorbable) implants. In the case of segmental defects or other serious fractures to a load bearing bone, such as a tibia or femur, managing the challenges recited above and others to find an appropriate balance of strength, biocompatibility, bioabsorbability and patient comfort can be particularly complicated.